The reason why smd led susceptible to moisture is that they are made of materials that are easy to absorb moisture. When it is exposed to the air for a long time, water vapor and a small amount of moisture in the air will be brought into the LED device. During reflow soldering, the steam expands rapidly because of moisture, and the encapsulation colloid will generate internal stress, which acts on the bonding wire (gold wire), When the stress is greater than the tensile strength of the bonding wire, the bonding wire is disconnected instantly, resulting in damage to the internal circuit of the smd led, resulting in a dead light.
There is also a problem of moisture erosion in outdoor applications, especially in the rainy season, if the smd led is not used for a long time, the temperature inside the lamp and the leds will be low, and the external moisture will pass through the potting glue, or the gap will enter the led foot, and penetrate into the inside of the smd led, and the water vapor brings trace elements into the leds. At the moment when the led is energized, under the action of the electric field, the electrolytic water reaction occurs at the chip electrode, resulting in ion migration, which causes the chip electrode to be gradually corroded. The initial performance is leakage, the brightness becomes low, flicker appears in the middle stage, and open circuit appears in the late stage, and there is a lack of color. If you use it frequently, the inside of the LED will generate temperature, and it will automatically discharge moisture, keep it dry, and the smd led will stay on for a long time. What should I do if I don't use it for a long time?
Please lower the current through the controller first, keep it within 5mA, light up the micro-current for 7 consecutive days, and then gradually increase the current.
In order to improve everyone's understanding of the characteristics of smd led, and ensure customers to master led's characteristics during use, and minimize or avoid unnecessary product damage caused by human/environmental factors. Specially explained here.
1.SMD LED PACKAGE
Smd led products are packaged in moisture-proof and anti-static aluminum foil bags. During shipment, avoid squeezing and piercing the packaging bags to cause air leakage in the moisture-proof bags.
2.Unopened smd led storage
Try not to store unopened smd led for a long time, because the storage environment is not easy to control. The recommended storage environment is to choose a moisture-proof cabinet, the temperature is ≤30 ℃, and the humidity is below 60%. In this case, RGB smd leds can be stored for 30 days, and white smd leds can be stored for 60 days, and make sure smd led can be used up within this period. Regardless of whether the storage time has expired, be sure to conduct a first-piece test before production.
If the smd led has not been used for 6 months, it is recommended to use oven baking and dehumidification before using it again (recommended dehumidification conditions should be adjusted according to the product)
3.Precautions after unpacking
Due to the different storage environments of warehouses, it is not recommended to make large quantities of stockpiles. Please accurately calculate the demand for the production line. Please use up the leds within 24 hours after opening the package. After the package is unpacked, the unused smd led should be vacuum sealed again, stored in a 60 ℃ oven or placed in a moisture-proof cabinet, the temperature should be ≤30 ℃, and the humidity should be below 60%.
4.SMT precautions
①.Static Protection
Please wear an anti-static wristband, the wristband must be grounded reliably, and all production desktops, equipment and production instruments must be grounded; grounding requirements: grounding resistance should not be greater than 1 ohm.
②.Workshop environmrnt temperature
When the smd led is unpacked for SMT, it is already exposed to the workshop environment. It is recommended to control the workshop environment: temperature <30℃, humidity <60%RH.
